Vitamin K Vitamin K Vitamin K is a

Vitamin K

Vitamin K • Vitamin K is a fat-soluble vitamin which plays a vital role in the coagulation system. Two natural forms of vitamin K: • Vitamin K 1( phylloquinone): from vegetable and animal sources. • Vitamin K 2 ( menaquinone): which is synthesized by bacterial flora.

Sources and daily requirements • Sources of vitamin K : green leafy vegetables such as spinach, margarine, liver and vegetable oils like olive, canola, and soybean oils. • Daily requirement : 100 μg /d.

RDA is 100 μg /d.

Functions of vitamin K • Vitamin K in it’s active form (hydroquinone) is required for carboxylation of glutamic acid, which is necessary for calcium binding to some important coagulation proteins such as prothrombin (factor II) , factors VII, IX, and X , protein C and protein S.

Metabolism of vitamin K Hydroquinone Ca++ active coagulation proteins

Vitamin K deficiency Causes of vitamin K deficiency: 1. Malabsorption (celiac disease, Crohn's) 2. Obstructive biliary diseases. 3. Use of broad-spectrum antibiotic. 4. Prematurity. 5. Drugs ( warfarin , orlistat )

Clinical features of vitamin K deficiency • The main symptom of vitamin K deficiency is hemorrhage. ( bruises, hematemesis, melena hematuria, prolong bleeding after circumcision, epistaxis, intracranial hemorrhage) • Newborn infants (1– 7 days after birth) are particularly susceptible to vitamin K deficiency (hemorrhagic disease of the newborn).

Diagnosis of vitamin K deficiency • • Clinical features. Elevated prothrombin time ( PT ). Reduced level of clotting factors( II, X, IX, VII). Vitamin K level may also be measured directly by HPLC.

Treatment • Vitamin K 10 mg IM or IV. • For patients with sever bleeding FFP or blood transfusion may be required.

Prevention • Vitamin K (1 mg IM) is given prophylactically at birth for newborn babies. • Chronic malabsorption, 1– 2 mg/d of vitamin K should be given orally, or 1– 2 mg/week parenterally.

Vitamin E

Vitamin E • Vitamin E is a fat soluble vitamin which acts as an antioxidant.

Vitamin E Two isoforms: • Tocopherols. • Tocotrienols. • Only tocopherol meets human requirements.

Sources and daily requirement • Sources : sunflower oil, soybean, corn oils, meats, nuts, cereal grains, and small amounts are present in fruits and vegetables. • The daily requirement of vitamin E is 15 mg/d.

The daily requirement of vitamin E is 15 mg/d

Functions of vitamin E • Vitamin E protects low-density lipoproteins (LDLs) and polyunsaturated fats in cell membranes (nerve cells, RBCs ) from oxidation. • Increase sexual performance. • Improve immune function. • Prevent cardiovascular disease. • Slow aging process.

Vitamin E deficiency It is extremely rare seen only in : • Severe and prolonged malabsorptive diseases (celiac disease, cystic fibrosis). • Prolonged cholestasis. • Familial vitamin E deficiency due to defect in the tocopherol transport protein.

Clinical features of vitamin E deficiency • Peripheral neuropathy characterized by areflexia, ataxic gait, decreased vibration and position sensations. • Ophthalmoplegia. • Skeletal myopathy. • Retinopathy. • Hemolytic anemia. • Increased susceptibility for certain viral infections.

Diagnosis and treatment • Diagnosis : low blood level of tocopherol. • Treatment : 800– 1200 mg of tocopherol per day. • Higher doses may be required for patients with malabsorption.

Vitamin E Toxicity • High doses of vitamin E (>800 mg/d) may reduce platelet aggregation and interfere with vitamin K metabolism and are therefore contraindicated in patients taking warfarin.

Water soluble vitamins

Vitamin C

Vitamin C • Vitamin C is a water soluble vitamin which plays a vital role in connective tissue metabolism.

Vitamin C Tow biologically active forms: • Ascorbic acid. • Dehydroascorbic acid.

Sources and daily requirements • Sources of vitamin C include : Citrus fruits, green vegetables, tomatoes, and potatoes. • The daily requirement: 90 mg/d for males and 75 mg/d for females. • Smoking, hemodialysis, pregnancy, stress (infection, trauma) and drugs like steroids and NSAID appear to increase vitamin C requirements.

Functions of vitamin C • Connective tissue metabolism and crosslinking (proline hydroxylation). • Antioxidant activity (protect against cancer). • Promotion of nonheme iron absorption.

Functions of vitamin C • The conversion of dopamine to norepinephrine. • Synthesis of many peptide hormones. • Is a component of many enzyme systems. • In high doses decrease the severity of respiratory tract infection.

Vitamin C deficiency • Vitamin C deficiency causes Scurvy which is primarily reflect impaired formation of mature connective tissue. Causes of vitamin C deficiency: • Malnutrition (lack of fresh fruits and vegetables for > 2 months). • Elderly and infants. • Alcoholics.

Clinical features of Scurvy • Bleeding into skin (petechiae, ecchymoses, perifollicular hemorrhages). • Inflamed and bleeding gums. • Bleeding into joints, the peritoneal cavity, GIT pericardium, and the adrenal glands. • Poor wound healing. • In children, vitamin C deficiency may cause impaired bone growth.

Diagnosis and treatment of Scurvy Diagnosis : • Clinical features. • Low plasma or leukocyte level of vitamin C. Treatment : • vitamin C (250 mg 8 hourly) improves the symptoms of scurvy within a matter of several days. • Encourage vitamin C rich diet.

Vitamin C toxicity • Acute toxicity : >2 g in a single dose may result in abdominal pain, diarrhea, and nausea. • Chronic toxicity : Chronic high-doses may result in an increased prevalence of kidney stones. • Chronic high doses may promote iron overload in patients taking supplemental iron. • High doses may induce hemolysis in patients with G 6 PD deficiency.